WO2011029795A1

WO2011029795A1 - Tilt control for tilting vehicles

Info

Publication number: WO2011029795A1
Application number: PCT/EP2010/063040
Authority: WO
Inventors: Frank Will
Original assignee: Ino8 Pty Ltd
Priority date: 2009-09-08
Filing date: 2010-09-06
Publication date: 2011-03-17
Also published as: CN102596697B; EP3192730B1; EP2475570A1; EP2475570B1; EP2628672A2; EP2628672A3; EP2628672B1; CN102596697A; EP3192730A1

Abstract

The invention relates to a tilting vehicle (10) including a frame (12) freely tiltable transversely between at least two spaced wheels (14, 114), at least one variable damper (28, 30, 148) with adjustable damping force operatively connected between the frame (12) and the two wheels (14, 114), at least one sensor to generate signals indicative of transverse tilting of the frame (12) relative to a central vertical plane of the vehicle, and a controller in communication with the at least one variable damper (28, 30, 148) and the at least one sensor. The controller is configured to vary transverse damping by the at least one variable damper (28, 30, 148) in accordance with the signals generated by the at least one sensor to passively provide transverse tilt stability to the frame (12) through the force generated in the damper in the opposite direction of the damper movement. The invention suggests to transversly damp a freely tiltable frame in accordance to a damping state for enhancing driving security and comfort of the vehicle.

Description

TILT CONTROL FOR TILTING VEHICLES FIELD OF THE INVENTION

The present invention relates to tilt control for tilting vehicles. BACKGROUND OF THE INVENTION

Tilting vehicles are subject to overturning transversely due to transverse forces such as side wind forces, transverse gravitational force components, and centrifugal forces. Active tilt control systems have been proposed to prevent transverse overturning. Such systems generally include transverse actuators to force the vehicle to tilt transversely to counteract transverse forces on the vehicle. Some existing solutions comprise a mechanical brake being in a brake state or open state, a manually operated tilt control. The solution usually is just a plausibility check that doesn't comprise any sensors to measure tilt angle or tilt rate and it can be activated either manually or by using a plausibility check, for example in case of an acceleration of the vehicle. Active tilt control systems are complicated and expensive.

What is needed is a solution which addresses the above difficulties. SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a tilting vehicle including a frame freely tiltable transversely between at least two spaced wheels, at least one variable damper with adjustable damping force operatively connected between the frame and the two wheels, at least one sensor to generate signals indicative of transverse tilting of the frame relative to a central vertical plane of the vehicle, and a controller in communication with the at least one variable damper and the at least one sensor, wherein the controller is configured to vary transverse damping by the at least one variable damper in accordance with the signals generated by the at least one sensor to passively provide transverse tilt stability to the frame through the force generated in the damper in the opposite direction of the damper movement. The invention suggests to transversely damp a freely tiltable frame in accordance to a damping state for enhancing driving security and comfort of the vehicle. The anti-tilting apparatus solely comprises at least one damper, at least one sensor and a controller for controlling the damper in accordance to the sensed tilting state of the vehicle. The anti-tilting apparatus is cheap, easy to use and can be refitted to existing vehicles. In contrast to known solutions the anti-tilting apparatus does not rely on a mechanical brake or an actively operated hydraulic system using actuators such as an electro motor, oil pump, hydraulic pressure reservoir or similar. The system is automatically controlled by a controller on response of a tilting state sensed by a tilting sensor, which can be a tilt-angle sensor, a tilt-velocity or a tilt-acceleration sensor. The system is energy efficient, operates in a semi-passive mode without additional power demand for driving actuators, whereby an active change of the tilting state can be powered by the operating weight of the vehicle and the driver. Only a slight operating electric power is needed for operating the controller and some switching elements such as hydraulic or pneumatic valves. The operating power can be provided by a small battery or accumulator, thus the system can be applied to a motorized as well as a non-motorized vehicle such as a bicycle or similar.

According to a favourable embodiment the two wheels can be transversely or longitudinally spaced from each other. In case of transversely spaced wheels the damper can ensure transverse stability against tilting while driving the vehicle or in a parking state. The two transversely spaced wheels define a horizontal axis being parallel to a road and define a reference axis for measuring of and counteracting against a tilting movement. In case of longitudinally spaced wheels the damper can counteract against longitudinal tilting as well as transversal tilting preferably in a steering state, for instance while driving a curve.

The vehicle can have at least three wheels, wherein the two wheels can be two front wheels longitudinally spaced from at least one rear wheel. The vehicle can be a Trike or a Three- wheeler, favourably a kind of three-wheeled motorcycle, electrobicycle, man-powered bicycle or similar vehicle. The vehicle can further include a steering assembly disposed between the frame and the two front wheels. The vehicle can further include a suspension assembly disposed between the steering assembly and the two front wheels. The vehicle can further include a transverse tilt linkage disposed between the steering assembly and the suspension assembly or between the suspension assembly and the two front wheels. The two front wheels can change their longitudinal alignment with respect to the vehicle's longitudinal axis for controlling the direction of movement. A suspension assembly can increase comfort and can reduce mechanical shocks to the vehicle's frame. A transverse tilt linkage can increase stability and rating of the vehicle's frame.

The steering assembly can be tiltably mounted relative to the at least one transverse beam to enable tilting of the vehicle. Thus the vehicle remains comfortably steerable in a tilted position. The at least one transverse beam can be operatively connected between the two front wheels and the steering assembly. Such a connection increases connection reliability between steering assembly and front wheels especially in rough driving conditions.

Alternatively, the suspension assembly can be disposed between the frame and the steering assembly. A transverse tilt linkage can be disposed between the frame and the suspension assembly or between the steering assembly and the suspension assembly. In this way the suspension assembly is in series connection with the transverse tilt linkage and can act additive to the function of the transverse tilt linkage.

The at least one variable damper can be transversely disposed between one end of the at least one transverse beam and any one of the frame, the suspension assembly and the steering assembly. In this way a relative movement of frame and transverse beam is defined through the damper movement and a mechanical variable linkage between frame and transverse beam is installed. The at least one variable damper can comprise two transversely disposed variable subdampers in a push-pull relationship. The two variable subdampers can have adjacent facing ends articulated to one end of the transverse beam and opposite ends articulated to opposite ends of any one of the frame, the suspension assembly or the steering assembly. Thus a damper relies on two counteracting subdampers which provides redundancy and enhances damping effects and operating range the damper. Alternatively, the transverse tilt linkage can include upper and lower transverse beams articulated together by a central link, which decreases stiffness of the linkage. The central link can form part of the frame or part of the steering assembly and the link can be connected to a generally central portion of each transverse beam. The suspension assembly can include two transversely spaced suspension struts disposed between the upper and lower transverse beam and the two front wheels, which can reduce damping forces of each suspension strut. The at least one variable damper can be transversely disposed between one end of at least one transverse beam and the central link. The at least one damper can comprise two transversely disposed variable subdampers in a push-pull relationship. The two variable dampers can have adjacent facing ends articulated to the central link and opposite ends articulated to opposite ends of the transverse beam, thus increasing damping effects and reliability of the suspension assembly.

At least one of the two variable dampers can be hydraulically or electrically operated, thus being controllable by a hydraulic or electric controlling system. At least one of the two variable dampers can be a double-acting hydraulic damper fluidly interconnected between both sides of the damper by a closed loop hydraulic circuit, A closed loop hydraulic circuit whereby a double-acting damper is passively driven by hydraulic fluid pressurized in a corresponding chamber of the same damper or another damper features a passive tilting system without actively operated devices as an oil pump thus reducing costs and complex actively operated actuators. The closed loop hydraulic circuit can include two two-way solenoid valves fluidly connected between the at least one double-acting hydraulic damper, and a reservoir fluidly connected between the two two-way solenoid valves. The two valves can easily be controlled, whereby in a failsafe-position the valves can stay open. The controller can be configured to control bi-directional fluid flow through the hydraulic circuit such that the passive damping forces of the damper is actively controllable by the controller

The closed loop hydraulic circuit can include an electro -rheologic fluid or a magneto- rheologic fluid and at least one electro rheologic valve or at least one magneto rheologic valve hydraulically connected between both sides of the at least one damper. By controlling the rheologic characteristics of the fluid, like the viscosity, the damping characteristics can be controlled or adjusted by an electric or magnetic field thus reducing mechanical parts and increasing reliability and response time of the suspension assembly.

The at least one sensor can be selected from a tilt sensor, a tilt speed sensor, a vehicle speed sensor, a steering angle sensor, a steering angle velocity sensor, a steering angle acceleration sensor, a side wind sensor and combinations thereof. The controller can give higher priority to the signal from the steering angle velocity sensor or the steering angle acceleration sensor than any other sensor. In this way the controller can consider signals of various sensors hierarchically, whereby signals of the steering angle velocity sensor as being crucial for driving safety have the highest priority.

The suspension assembly can comprise at least one shock absorber having a closed loop hydraulic circuit which includes a electro-rheo logic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of a piston of the at least one damper or a mechanical lock out device. By controlling the rheologic characteristics of the fluid, like the viscosity, the shock absorber characteristics can be controlled or adjusted by an electric or magnetic field thus reducing mechanical parts and increasing reliability and response time of the suspension assembly.

The vehicle can include at least one steering damper. The steering damper can be mounted within the steering assembly. The steering damper can reduce effects of sudden steering movements of the driver thus smoothing driving behaviour and increases driving safety.

The vehicle, preferably a vehicle with only two wheels can have at least one steering damper mounted between the steering wheel or handlebar and the frame, wherein the steering damper has a closed loop hydraulic circuit which includes a electro-rheologic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of the at least one damper. The controller can be configured to control bi-directional fluid flow through the at least one steering damper by controlling the position of the electro-rheologic valve or one magneto -rheo logic valve to thereby vary steering damping. Thus an extension and retraction of a damper can be controlled actively by an electric or magnetic field which can be powered by the vehicle's board electric system.

The rear wheel can be driven by a motor. The rear wheel can be steered. Driving a rear wheel can improve traction and driving dynamic of the vehicle,. A steerable rear wheel can improve steering capability of the vehicle. Driving one rear wheel is cheaper and less complex than driving two front wheels, whereby a vehicle having two transversely spaced front wheels and at least one rear wheel is an advantageous embodiment of the invention.

The steering assembly can include a steering stem which is backwardly inclined so that an upper end of the steering stem is disposed towards the front of the vehicle. During a tilt operation an inclined steering stem reduces tilt of the steering assembly such that tilt effects are reduced.

A solenoid activated mechanical tilting lockout can be provided to prevent tilting of the frame during parking. A fixation of the tiltable frame during parking can increase anti-theft security and can prevent damage of the vehicle. A mechanical lockout provides further redundancy in case the hydraulic system would leak after a long period without use, for example through biting attacks from animals.

The controller can be connected to the brake system of the vehicle to vary brake pressure by opening a by-pass valve in the brake system or by increasing the brake pressure with an active pump. In this way the controller can control tilting as well as breaking for increasing driving safety of the vehicle, for example in case one or more wheels wheel start loosing traction.

The controller can be connected to a powertrain control system of the vehicle to vary power and torque output from the power train to the wheels of the vehicle. The vehicle can have at least two different powertrains connected to at least two different wheels and that the torque of each of these powertrains can be controlled independently from each other. In this way the controller can control tilting as well as wheel torque for increasing driving safety of the vehicle.

The controller can be a fuzzy controller that executes a fuzzy logic algorithm. The controller can use look-up tables to control the position of the or each damper. By using fuzzy logic and/or look up tables the controller can control the tilting state of the vehicle in an intelligent way and can optimize tilting behaviour in different driving situations, for instance when driving with low or high velocity, driving upward or downward. The controller can consider weather and road conditions like wet streets, winding roads or similar and can control more intelligent.

The at least one variable damper can provide a continuously variable damping force in both directions of movement at zero velocity of the damper with a spread of at least 10 in a range between a maximum force of 1000N and a minimum force of 100N, or in case of a rotational damper a maximum torque of at least 70Nm and a minimum torque of 7Nm. Such a variable damping force can adapt reaction of the damping system to certain parameters as tilting angle and driving condition, whereby a force being optimal to a distinct driving state can be chosen.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a schematic of a tilting vehicle of an embodiment of the invention;

Figure 2 is a schematic diagram of a tilt linkage of the vehicle;

Figure 3 is a hydraulic circuit diagram of a passive tilt control system of the vehicle; Figure 4 is a schematic diagram of an alternative tilt linkage; and Figure 5 is a schematic diagram of another alternative tilt linkage. DETAILED DESCRIPTION

Figure 1 illustrates a tilting vehicle 10 of one embodiment of the invention. The vehicle 10 has a frame 12 manually or freely tiltable transversely between two transversely spaced front wheels 14. The vehicle 10 also has a motor-driven rear wheel not visible in Figure 1. The two front wheels 14 are steerable by a handlebar 16 connected to a steering assembly (not visible in Figure 1) disposed between the frame 12 and the two front wheels 14. The vehicle 10 also has a suspension assembly including two transversely spaced suspension struts 18 (one of which is visible in Figure 1) disposed between the steering assembly and the two front wheels 14.

A transverse tilt linkage 20 is disposed between the steering assembly and the suspension assembly. Referring to Figure 2, the transverse tilt linkage 20 includes upper and lower transverse beams 22, 24 articulated together by a central link 26. Two double-acting hydraulic dampers 28, 30 are transversely disposed in a push-pull relationship between the upper and lower transverse beams 22, 24. The two dampers 28, 30 have adjacent facing piston ends articulated to the central link 26 and opposite cap ends articulated to opposite ends of the upper transverse beam 22. Referring again to Figure 1, the suspension struts 18 are vertically disposed between the lower transverse beam 24 and the two front wheels 14.

The two double-acting hydraulic dampers 28, 30 are fluidly interconnected by a closed loop hydraulic circuit 32 illustrated in Figure 3. The closed loop hydraulic circuit 32 includes two two-way solenoid valves 34, 36 fluidly connected between the two double- acting hydraulic dampers 28, 30, and a reservoir 38 fluidly connected between the two two-way solenoid valves 34, 36.

A controller (not shown) is provided in communication with the two two-way solenoid valves 34, 36 and sensors (not shown) for generating signals indicative of transverse tilting of the frame 12. The sensors include, for example, a tilt sensor, a vehicle speed sensor, and a steering angle sensor. The controller is configured to control bi-directional fluid flow through the two two-way solenoid valves 34, 36 to vary transverse damping by the two double-acting hydraulic dampers 28, 30 in accordance with signals generated by the sensors to passively provide transverse tilt stability to the frame 12. The controller is, for example, a fuzzy controller that executes a fuzzy logic algorithm. The fuzzy logic algorithm is, for example, based on calculated and/or measured dynamic transverse tilting characteristics of the vehicle 10.

In other embodiments (not shown), the suspension assembly is disposed between the frame and the steering assembly. According to these embodiments, a transverse tilt linkage is disposed between the frame and the suspension assembly or between the steering assembly and the suspension assembly for example.

With reference to Figures 4 and 5, other embodiments of the vehicle include a tilt linkage 144 disposed between the front wheels and the steering assembly. At least one transverse beam 146 may be operative ly connected between the two front wheels 114 and the steering assembly 142 as can be seen in Figure 4, or alternatively it can be connected otherwise as can be seen in Figure 5. The steering assembly 142 is tiltably connected relative to the transverse beam 146 with a bearing 150 to enable tilting of the vehicle.

At least one variable damper 148 can be transversely disposed between one end of the at least one transverse beam 146 and any one of the tilting frame (not shown), the suspension assembly 140 and the steering assembly 142, for example. Two transversely disposed variable subdampers (not shown), may for example be provided in a push-pull relationship and have adjacent facing ends articulated to one end of the transverse beam 146 and opposite ends articulated to opposite ends of any one of the tilting frame (not shown), the suspension assembly 140 or the steering assembly 142. The two subdampers act as one damper.

At least one of the variable dampers may, for example, be a double-acting hydraulic damper fluidly interconnected between both sides of the piston by a closed loop hydraulic circuit. The closed loop hydraulic circuit includes, for example, two two-way solenoid valves fluidly connected between the two double-acting hydraulic dampers, and a reservoir fluidly connected between the two two-way solenoid valves. The closed loop hydraulic circuit includes, for example, an electro-rheologic fluid or a magneto -rheo logic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of at least one damper piston.

The controller (not shown) is configured to control bi-directional fluid flow through the two two-way solenoid valves or the electro rheologic valve or one magneto rheologic valve to thereby vary transverse damping by at least one double-acting hydraulic damper.

The at least one sensor (not shown) is selected from, for example, a tilt sensor, a tilt speed sensor, a vehicle speed sensor, a steering angle sensor, a steering angle velocity sensor, a steering angle acceleration sensor, a side wind sensor and combinations thereof.

In some embodiments, the controller gives higher priority to the signal from the steering angle velocity sensor or the steering angle acceleration sensor than any other sensor.

The suspension assembly 140 may, for example, comprise at least one shock absorber (not shown) having a closed loop hydraulic circuit which includes, for example, a electro- rheologic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of a piston of the at least one damper or a mechanical lock out device (not shown).

In some embodiments, the vehicle includes at least one steering damper. The steering damper may be mounted within the steering assembly, for example. In some embodiments, the steering damper of the vehicle, or a vehicle with only two wheels with at least one steering damper mounted between the steering wheel or handlebar and the frame, has a closed loop hydraulic circuit which includes a electro-rheologic fluid or a magneto- rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of the at least one damper. In some embodiments, the controller (not shown) may be configured to control bidirectional fluid flow through the steering damper by controlling the position of the electro-rheologic valve or one magneto-rheologic valve to thereby vary steering damping by at least one double-acting hydraulic damper.

In some embodiments, the rear wheel is driven by a motor. In other embodiments, the rear wheel can be steered to simplify the tilting mechanism of the vehicle.

In some embodiments, the steering assembly includes a steering stem which is backwardly inclined so that an upper end of the steering stem is disposed towards the front of the vehicle.

In some embodiments, a mechanical tilting lockout (not shown) may be provided to prevent tilting of the frame during parking. The mechanical tilting lockout may, for example, by activated by a solenoid.

In some embodiments, the controller is connected to the brake system (not shown) of the vehicle and to vary brake pressure by opening a by-pass valve in the brake system or by increasing the brake pressure with an active pump.

In some embodiments, the controller (not shown) is connected to a powertrain control system of the vehicle to vary power and torque output from the power train to the wheels of the vehicle. The vehicle has at least two different powertrains connected to at least two different wheels and that the torque of each of these powertrains can be controlled independently from each other.

In some embodiments, the controller (not shown) is a fuzzy controller that executes a fuzzy logic algorithm. In some embodiments the controller uses look-up tables to control the position of the or each damper.

In other embodiments, the variable damper provides, for example, a continuously variable damping force in both directions of movement at zero velocity of the damper with a spread of at least 10 in a range between a maximum force of 1000N or higher and a minimum force of 100N or lower, or in case of a rotational damper a maximum torque of at least 70Nm or more and a minimum torque of 7Nm or less.

In other embodiments, the tilting vehicle includes a frame freely tiltable transversely between at least two longitudinally spaced wheels. The vehicle includes at least one variable damper with adjustable damping force operatively connected between the frame and the at least two wheels, at least one sensor to generate signals indicative of transverse tilting of the frame relative to a central vertical plane of the vehicle, and a controller in communication with the at least one variable damper and the at least one sensor. The controller is configured to vary transverse damping by the at least one variable damper in accordance with the signals generated by the at least one sensor to passively provide transverse tilt stability to the frame through the force generated in the damper in the opposite direction of the damper movement.

In this embodiment, the vehicle can further include at least one steering damper, the steering damper having a closed loop hydraulic circuit which includes a electro-rheologic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheo logic valve hydraulically connected between both sides of the at least one damper.

Embodiments of the invention passively provide tilting vehicles with transverse tilt stability, and thereby obviate the necessity of complicated and expensive active tilt control systems.

The embodiments have been described by way of example only and modifications are possible within the scope of the claims which follow. For example, the at least one damper may be electrical or pneumatic. The at least one damper may also be rotational.

Claims

1. A tilting vehicle (10) including a frame (12) freely tiltable transversely between at least two spaced wheels (14, 114), at least one variable damper (28, 30, 148) with adjustable damping force operatively connected between the frame (12) and the two wheels (14, 114), at least one sensor to generate signals indicative of transverse tilting of the frame (12) relative to a central vertical plane of the vehicle, and a controller in communication with the at least one variable damper (28, 30, 148) and the at least one sensor, wherein the controller is configured to vary transverse damping by the at least one variable damper (28, 30, 148) in accordance with the signals generated by the at least one sensor to passively provide transverse tilt stability to the frame (12) through the force generated in the damper in the opposite direction of the damper movement.

2. A vehicle according to claim 1, wherein the two wheels (14, 114) are transversely spaced from each other.

3. A vehicle according to claim 1, wherein the two wheels (14, 114) are longitudinally spaced from each other.

4. A vehicle according to claim 2, wherein the vehicle (10) has at least three wheels, and wherein the two transversely spaced wheels are two front wheels (14, 114) longitudinally spaced from at least one rear wheel.

5. A vehicle according to claim 4, further including a steering assembly (142) disposed between the frame (12) and the two front wheels (14, 114).

6. A vehicle according to claim 5, further including a suspension assembly (140) disposed between the steering assembly (142) and the two front wheels (14, 114).

7. A vehicle according to claim 6, further including a transverse tilt linkage (20) disposed between the steering assembly (142) and the suspension assembly (140) or between the suspension assembly (142) and the two front wheels (14, 114).

8. A vehicle according to claim 7, wherein the steering assembly (142) is tiltably mounted relative to at least one transverse beam (22, 24, 146) to enable tilting of the vehicle (10).

9. A vehicle according to claim 8, wherein the at least one transverse beam (22, 24, 146) is operatively connected between the two front wheels (14, 114) and the steering assembly (142).

10. A vehicle according to claim 5, further including a suspension assembly (140) disposed between the frame (12) and the steering assembly (142).

11. A vehicle according to claim 10, further including a transverse tilt linkage (20) disposed between the frame (12) and the suspension assembly (140) or between the steering assembly (142) and the suspension assembly (140).

12. A vehicle according to claim 9 or claim 11, wherein the at least one variable damper (28, 30, 148) is transversely disposed between one end of the at least one transverse beam (22, 24, 146) and any one of the frame (12), the suspension assembly (140) and the steering assembly (142).

13. A vehicle according to claim 12, wherein the at least one variable damper (28, 30, 148) comprises two transversely disposed variable subdampers in a push-pull relationship.

14. A vehicle according to claim 13, wherein the two variable subdampers have adjacent facing ends articulated to one end of the transverse beam (22, 24, 146) and opposite ends articulated to opposite ends of any one of the frame (12), the suspension assembly (140) or the steering assembly (142).

15. A vehicle according to claim 9 or claim 11, wherein the transverse tilt linkage (20) includes upper and lower transverse beams (22, 24) articulated together by a central link (26).

16. A vehicle according to claim 15, wherein the central link (26) forms part of the frame (12) or part of the steering assembly (142) and the link is connected to a generally central portion of each transverse beam (22, 24).

17. A vehicle according to claim 16, wherein the suspension assembly (140) includes two transversely spaced suspension struts (18) disposed between the upper and lower transverse beam (22, 24) and the two front wheels (14, 114).

18. A vehicle according to any of claims 15 to 17, wherein the at least one variable damper (28, 30, 148) is transversely disposed between one end of at least one transverse beam (22, 24) and the central link (26).

19. A vehicle according to claim 18, wherein the at least one variable damper (28, 30, 148) comprises two transversely disposed variable subdampers in a push-pull relationship.

20. A vehicle according to claim 19, wherein the two variable subdampers have adjacent facing ends articulated to the central link (26) and opposite ends articulated to opposite ends of the transverse beam (22, 24).

21. A vehicle according to claim 13, 14, 19 or 20, wherein at least one of the two variable subdampers is hydraulically or electrically operated.

22. A vehicle according to claim 21, wherein at least one of the two variable subdampers is a double-acting hydraulic damper fluidly interconnected between both sides of the damper by a closed loop hydraulic circuit.

23. A vehicle according to claim 21 or 22, wherein the closed loop hydraulic circuit (32) includes two two-way solenoid valves (34, 36) fluidly connected between the at least one double-acting hydraulic damper (28, 30, 148), and a reservoir fluidly connected between the two two-way solenoid valves (34, 36).

24. A vehicle according to claim 23, wherein the controller is configured to control bidirectional fluid flow through the hydraulic circuit (32).

25. A vehicle according to claim 24, wherein the closed loop hydraulic (32) circuit includes an electro-rheologic fluid or a magneto -rheologic fluid and at least one electro rheologic valve or at least one magneto rheologic valve hydraulically connected between both sides of the at least one damper (28, 30, 148).

26. A vehicle according to any preceding claim, wherein the at least one sensor is selected from a tilt sensor, a tilt speed sensor, a vehicle speed sensor, a steering angle sensor, a steering angle velocity sensor, a steering angle acceleration sensor, a side wind sensor and combinations thereof.

27. A vehicle according to claim 26, wherein the controller gives higher priority to the signal from the steering angle velocity sensor or the steering angle acceleration sensor than any other sensor.

28. A vehicle according to any one of claims 6 to 27, wherein the suspension assembly (140) comprises at least one shock absorber having a closed loop hydraulic circuit (32) which includes a electro-rheologic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of a piston of the at least one damper (28, 30, 148) or a mechanical lock out device.

29. A vehicle according to any of the preceding claims, further including at least one steering damper.

30. A vehicle according to claim 29 when appended to any one of claims 5 to 28, wherein the steering damper is mounted within the steering assembly (142).

31. A vehicle according to claim 29 or 30, preferably a vehicle with only two wheels with at least one steering damper mounted between the steering wheel (14, 114) or handlebar (16) and the frame (12), wherein the steering damper has a closed loop hydraulic circuit (32) which includes a electro-rheologic fluid or a magneto-rheologic fluid and at least one electro rheologic valve or one magneto rheologic valve hydraulically connected between both sides of the at least one steering damper.

32. A vehicle according to any one of claims 29 to 31, wherein the controller is configured to control bi-directional fluid flow through the at least one steering damper by controlling the position of the electro-rheologic valve or one magneto-rheologic valve to thereby vary steering damping.

33. A vehicle according to any one of claims 4 to 32, wherein the rear wheel is driven by a motor.

34. A vehicle according to any one of claims 4 to 33, wherein the rear wheel can be steered.

35. A vehicle according to any of claims 5 to 34, wherein the steering assembly includes a steering stem which is backwardly inclined so that an upper end of the steering stem is disposed towards the front of the vehicle (10).

36. A vehicle according to any preceding claim, further including a solenoid activated mechanical tilting lockout to prevent tilting of the frame during parking.

37. A vehicle according to any preceding claim, wherein the controller is connected to the brake system of the vehicle to vary brake pressure by opening a by-pass valve in the brake system or by increasing the brake pressure with an active pump.

38. A vehicle according to any preceding claim wherein the controller is connected to a powertrain control system of the vehicle to vary power and torque output from the power train to the wheels of the vehicle (10).

39. A vehicle according to claim 38, wherein the vehicle (10) has at least two different powertrains connected to at least two different wheels and that the torque of each of these powertrains can be controlled independently from each other.

40. A vehicle according to any preceding claim, wherein the controller is a fuzzy controller that executes a fuzzy logic algorithm.

41. A vehicle according to any preceding claim, wherein the controller is using look-up tables to control the position of the or each damper.

42. A vehicle according to any preceding claim, wherein the at least one variable damper (28, 30, 148) provides a continuously variable damping force in both directions of movement at zero velocity of the damper (28, 30, 148) with a spread of at least 10 in a range between a maximum force of 1000N and a minimum force of 100N, or in case of a rotational damper a maximum torque of at least 70Nm and a minimum torque of 7Nm.